ON PETITION FOR REHEARING
STEPHEN H. ANDERSON, Circuit Judge.This case is before us on rehearing to consider the application of two decisions by the United States Supreme Court, McCarthy v. Bronson, — U.S. —, 111 S.Ct. 1737, 114 L.Ed.2d 194 (1991), and Peretz v. United States, — U.S. —, 111 S.Ct. 2661, 115 L.Ed.2d 808 (1991), issued since the previous opinion by the panel in this case. Clark v. Poulton, 914 F.2d 1426 (10th Cir.1990). Upon review of those authorities, we grant the petition for rehearing, withdraw our previous opinion and substitute the following opinion.
James E. Clark brought this suit under 42 U.S.C. § 1983 against the Adult Parole Division of the Utah State Corrections Department, parole officer Robert Poulton, the Salt Lake County jail, and David Jor-gensen, a transportation officer employed at the jail. Clark alleged that his constitutional rights were violated by two separate incidents of excessive force, and by the denial of medical treatment and of reasonable access to the mails during his pretrial detention in the jail.1 The district court referred the case to a magistrate judge pursuant to 28 U.S.C. § 636(b)(1)(B). The magistrate judge held an evidentiary hearing and submitted a report recommending that Clark’s claims be dismissed. The district court made a de novo review of the record, adopted the magistrate judge’s report and entered judgment accordingly. Clark appeals, asserting that the magistrate judge had no jurisdiction because the referral was not authorized by statute, that in any event the district court failed to conduct a proper de novo review of the portion of the report to which Clark had objected, and that the magistrate judge erred in his application of the law. We hold that (1) the referral was authorized by statute; (2) in any event Clark waived his right to object to the magistrate judge’s authority by failing to object below; and (3) the district court conducted a proper review of the magistrate judge’s report. We therefore affirm the dismissal of Clark’s claims.
BACKGROUND
The relevant facts are undisputed. While on parole following state court convictions, Clark returned to Salt Lake City after an out-of-state visit approved by his parole officer, defendant Poulton, and learned that the police were looking for him in connection with two armed robberies. The day after Clark returned, he reported to Poulton at the Salt Lake County Parole office. Poulton then arrested him on suspicion of the armed robberies, handcuffed him, and took him down the hall to be booked. When Clark objected during the booking to being photographed without an attorney, Poulton allegedly pushed *1363Clark against the wall and lifted his handcuffed arms over his head, aggravating a previous back injury. Following his transportation to the Salt Lake County jail, Clark purportedly did not receive requested medical treatment for his back for several weeks.
While detained in the jail, Clark and several other inmates were transported to court by defendant Jorgensen. On leaving the courtroom, Clark asked to use the restroom and Jorgensen told him he would have to wait. Because of previous surgery, waiting was apparently difficult and uncomfortable for Clark and he later doubled over in the courthouse elevator. Jor-gensen allegedly grabbed Clark’s neck and chest and pushed him into the elevator wall, again aggravating his back injury. Clark required physical therapy for a year after his release from jail and sought recovery of these medical expenses as part of his damages.
Clark’s original complaint was filed May 12, 1986. On May 14, the district court entered an order of reference which stated:
IT IS ORDERED that as authorized by 28 U.S.C. § 636(b)(1)(B) and the rules of this court the above entitled case is referred to the magistrate. He is directed to manage the case, to receive all motions filed, hear oral arguments hereon, to conduct evidentiary hearings when proper and make proposed findings of fact, and to submit to the undersigned judge a report and recommendation for the proper resolution of dispositive matters presented.
R.Vol. I, doc. 2. Pursuant to the order, the magistrate judge thereafter determined that Clark could proceed in forma pauperis, appointed him counsel, held scheduling and pretrial conferences, conducted an eviden-tiary hearing (described in the relevant documents as a trial), and issued a report recommending that Clark’s claims be dismissed. Clark objected to the report, which the district court adopted in all respects, after reviewing the record.
DISCUSSION
I. Propriety of Reference to Magistrate Judge
Clark first asserts that the magistrate judge had no jurisdiction over his case because the referral was not authorized by the relevant statute, 28 U.S.C. § 636(b)(1)(B). Our analysis of this issue necessitates a review of the jurisdiction and authority of a federal magistrate judge under section 636.
Section 636(b)(1)(A) authorizes a judge to designate a magistrate judge to hear and determine any pretrial matter except for certain dispositive motions listed therein.2 The district court reviews a section 636(b)(1)(A) determination to determine whether the “magistrate’s order is clearly erroneous or contrary to law.” Id.
Section 636(b)(1)(B) authorizes a judge to designate a magistrate judge to conduct evidentiary hearings and submit proposed findings and recommendations in three types of proceedings: (1) those dispositive motions excepted in section 636(b)(1)(A); (2) applications for post-trial relief by criminal defendants; and (3) prisoner petitions challenging conditions of confinement.3 If a party objects to the magistrate judge's proposed findings and recommendations, the district court must “make a de novo deter*1364mination of those portions of the report or specified proposed findings or recommendations to which objection is made.” 28 U.S.C. § 636(b)(1).
Section 636(b)(2) authorizes designation of a magistrate judge to serve as a special master, either pursuant to the Federal Rules of Civil Procedure or, upon consent of the parties, without regard to Rule 53(b) of the Federal Rules of Civil Procedure.
Section 636(b)(3) provides that “[a] magistrate may be assigned such additional duties as are not inconsistent with the Constitution and laws of the United States.” The parameters of this “catch-all” provision are relevant to our decision in this case.
Finally, section 636(c)(1) provides that “[u]pon the consent of the parties, a ... magistrate ... may conduct any or all proceedings in a jury or nonjury civil matter and order the entry of judgment in the case, when specially designated to exercise such jurisdiction by the district court or courts he serves.” 28 U.S.C. § 636(c)(1).4 A party may appeal a judgment entered under this section to either the district court or a court of appeals, in the same way in which a district court judgment is appealed to the court of appeals. 28 U.S.C. § 636(c)(3), (4).
At issue in this case are Clark’s two claims based on excessive force, one of which occurred at the Salt Lake County Parole Office after Clark’s parole officer arrested him and while he was being booked, and the other which occurred during Clark’s pretrial detention in jail. As indicated, the district court referred the matter to the magistrate judge under section 636(b)(1)(B), evidently treating this case as a conditions-of-confinement case.
A. Section 636(b)(1)(B)—Conditions of Confinement:
Section 636(b)(1)(B) authorizes referral to a magistrate judge of “prisoner petitions challenging conditions of confinement.” The propriety of such a referral therefore involves two subsidiary questions: (1) whether “conditions of confinement” encompasses only ongoing prison conditions or whether it extends to isolated instances of alleged mistreatment; and (2) whether “confinement” is present—that is, whether the challenged incident occurred while the prisoner was in “confinement.” We address each question in turn.
1. Isolated Incidents.
The propriety of the referral to the magistrate judge of Clark’s two individual and isolated claims of excessive force is controlled by McCarthy v. Bronson, — U.S. —, 111 S.Ct. 1737, 114 L.Ed.2d 194 (1991). The Supreme Court in McCarthy granted certiorari “to decide whether ... authorization [under 28 U.S.C. § 636(b)(1)(B)] includes cases alleging a specific episode of unconstitutional conduct by prison administrators or encompasses only challenges to ongoing prison conditions.” 111 S.Ct. at 1739. The Court concluded that “conditions of confinement” cases under section 636(b)(1)(B) include suits alleging that prison administrators acted unconstitutionally in an isolated incident or incidents. Clark’s claims therefore challenged “conditions” of confinement under McCarthy. We turn now to the question of whether Clark was in “confinement” when each incident occurred.
2. Confinement.
One of the incidents in this case occurred while Clark was detained, in handcuffs, at the Salt Lake County Parole Of*1365fice, shortly after he was arrested. The other took place while he was in pretrial detention. There is no doubt that Clark was in “confinement” for purposes of section 636(b)(1)(B) when he was in pretrial detention. “[T]he Due Process Clause of its own force requires that conditions of confinement satisfy certain minimal standards for pretrial detainees....” Collins v. City of Harker Heights, — U.S. —, —, 112 S.Ct. 1061, 1070, 117 L.Ed.2d 261 (1992) (emphasis added). See also Wimmer v. Cook, 774 F.2d 68, 69, 74 (4th Cir.1985) (pretrial detention); Worley v. Sharp, 724 F.2d 862, 863 (10th Cir.1983) (per curiam) (same). Thus, referral of the excessive force claim occurring while he was in pretrial detention was authorized by section 636(b)(1)(B). We need not reach the question of whether Clark was in “confinement” while he was being booked because, as we explain infra, referral of both claims was proper under section 636(b)(3).
B. Section 636(b)(3) — Additional Duties:
Section 636(b)(3) permits magistrate judges to be assigned “such additional duties as are not inconsistent with the Constitution and laws of the United States.” It is a “ ‘catchall’ provision.” Garcia v. Boldin, 691 F.2d 1172, 1178 (5th Cir.1982); accord, e.g., King v. Ionization Int'l, Inc., 825 F.2d 1180, 1185 (7th Cir.1987). “Where the district court is not specifically empowered to refer a case, it may do so under the general provision of 28 U.S.C. § 636(b)(3)....” Hall v. Vance, 887 F.2d 1041, 1046 (10th Cir.1989).
The legislative history of the original Federal Magistrate’s Act, as well as the 1976 amendments to the Act, confirm the expansiveness of subsection (b)(3). In Mathews v. Weber, 423 U.S. 261, 96 S.Ct. 549, 46 L.Ed.2d 483 (1976), the Supreme Court reviewed the legislative history of the original Act:
The three examples § 636(b) sets out are, as the statute itself states, not exclusive. The Senate sponsor of the legislation, Senator Tydings, testified in the House hearings:
“The Magistrate[s] Act specifies these three areas because they came up in our hearings and we thought they were areas in which the district courts might be able to benefit from the magistrate’s services. We did not limit the courts to the areas mentioned....
We hope and think that innovative, imaginative judge who want to clean up their caseload backlog will utilize the U.S. magistrates in these areas and perhaps even come up with new areas to increase the efficiency of their courts.”
Id. at 267, 96 S.Ct. at 553 (quoting Hearings on the Federal Magistrates Act Before Subcomm. No. 4 of the House Comm. on the Judiciary, 90th Cong., 2d Sess. 81 (1968)). Similarly, the legislative history of the 1976 amendments states:
This subsection [(b)(3)] enables the district courts to continue innovative experimentations in the use of this judicial officer. At the same time, placing this authorization in an entirely separate subsection emphasizes that it is not restricted in any way by any other specific grant of authority to magistrates.
H.R.Rep. No. 1609, 94th Cong., 2d Sess. 12, reprinted in 1976 U.S.Code Cong. & Admin.News 6162, 6172 (emphasis added). Most recently, the Supreme Court in Peretz noted the breadth of the “additional duties” section:
The generality of the category of “additional duties” indicates that Congress intended to give federal judges significant leeway to experiment with possible improvements in the efficiency of the judicial process that had not already been tried or even foreseen. If Congress had intended strictly to limit these additional duties to functions considered in the committee hearings or debates, presumably it would have included in the statute a bill of particulars rather than a broad residuary clause.
Peretz, 111 S.Ct. at 2667; see also Government of the Virgin Islands v. Williams, 892 F.2d 305, 310 (3d Cir.1989) (“The plain language of this statute clearly confers upon federal magistrates the jurisdiction to assume virtually any judicial duty assigned *1366to them by the district courts, so long as that assignment is neither unconstitutional nor a violation of some other federal law.”), cert. denied, 495 U.S. 949, 110 S.Ct. 2211, 109 L.Ed.2d 537 (1990). The statutory authorization for referring to magistrate judges prisoner petitions challenging conditions of confinement was not meant as a bar to the referral of prisoner petitions unrelated to conditions of confinement. See, e.g., John v. Louisiana, 899 F.2d 1441, 1446 (5th Cir.1990) (subsection (b)(3) authorizes post-trial referral of sanctions question even though subsection (b)(1)(A) only refers to pretrial matters).
Gomez v. United States, 490 U.S. 858, 109 S.Ct. 2237, 104 L.Ed.2d 923 (1989), does not compel a contrary conclusion. There, the Court concluded that “the carefully defined grant of authority to conduct trials of civil matters and of minor criminal cases should be construed as an implicit withholding of the authority to preside at a felony trial,” id. at 872, 109 S.Ct. at 2245, because
[w]hen a statute creates an office to which it assigns specific duties, those duties outline the attributes of the office. Any additional duties performed pursuant to a general authorization in the statute reasonably should bear some relation to the specified duties.
Id. at 864, 109 S.Ct. at 2241. Presiding over a felony trial bears no relation to the duties specified in the statute, but presiding over a prisoner's section 1983 action does.
Peretz supports this interpretation of Gomez:
Because the specified duties that Congress authorized magistrates to perform without the consent of the parties were not comparable in importance to supervision of felony trial voir dire but were instead ‘subsidiary matters,’ we did not waver from our conclusion that a magistrate cannot conduct voir dire over the defendant’s objection.
Peretz, 111 S.Ct. at 2667 (citation omitted). Because Clark’s section 1983 action challenging his treatment while being booked and while in pretrial detention is “comparable in importance” to a prisoner petition challenging conditions of confinement, construed in McCarthy to include individual instances of alleged mistreatment, we believe the referral to the magistrate judge under section 636(b)(3) was proper.5 Furthermore, as the statute, the cases, and legislative history make clear, there is a need for district courts to have maximum flexibility in referring matters to magistrate judges to aid the district courts in dealing with the demands of heavy case loads, and for other compelling purposes of the administration of justice. The referral here advanced that settled purpose.
II. Waiver
Moreover, Clark made no objection to the referral to the magistrate judge. Therefore, assuming arguendo that there was no statutory authorization for the referral, the issue was waived by Clark’s failure to object below.
While it is true that the Supreme Court in Gomez used the term “jurisdiction” to describe the magistrate judge’s authority,6 *1367it is also clear that the Court was not using the term “jurisdiction” in the sense of non-waivable subject matter jurisdiction. See Peretz, 111 S.Ct. at 2678 (Scalia, J., dissenting) (“We used [the term ‘jurisdiction’] in Gomez as a synonym for ‘authority/ not in the technical sense involving subject-matter jurisdiction.”); United States v. Wey, 895 F.2d 429, 431 (7th Cir.) (“Gomez used the word ‘jurisdiction’ in a context revealing that the court meant ‘authority.’ ”), cert. denied, — U.S. —, 110 S.Ct. 3283, 111 L.Ed.2d 792 (1990). Indeed, although the Court in Peretz specifically declined to address the question of whether an unauthorized referral is a matter of jurisdiction and therefore not subject to waiver,7 the Court’s analysis suggests that it views Gomez as not implicating subject matter jurisdiction. “In holding that a magistrate can conduct voir dire where the parties consent, the Court [in Peretz] cannot have interpreted Gomez as implicating subject matter jurisdiction of the courts; it is well-established that litigants cannot confer jurisdiction by consent where none exists.” United States v. Judge, 944 F.2d 523, 525 (9th Cir.1991) (citing Insurance Corp. of Ireland v. Compagnie des Bauxites, 456 U.S. 694, 701-02, 102 S.Ct. 2099, 2103-04, 72 L.Ed.2d 492 (1982)).
We thus agree with those circuit court cases which have considered the issue and held that a magistrate judge’s lack of statutory authority is not a jurisdictional defect, so any objection is waived if not raised. See, e.g., United States v. Judge, 944 F.2d 523 (9th Cir.1991); United States v. Musacchia, 900 F.2d 493, 503 (2nd Cir.1990) (“the improper reference to a magistrate is a waivable defect that must be raised within the time permitted by Fed.R.Crim.P. 12(c) or it is waived under Rule 12(b).”), cert. denied, — U.S. —, 111 S.Ct. 2887, 115 L.Ed.2d 1052 (1991); United States v. Wey, 895 F.2d 429, 431 (7th Cir.) (“We do not have a ‘jurisdictional’ problem.... We have at most a mistaken interpretation of a law designating which judicial officer shall preside over which proceedings.”), cert. denied, — U.S. —, 110 S.Ct. 3283, 111 L.Ed.2d 792 (1990); Mylett v. Jeane, 879 F.2d 1272, 1275 (5th Cir.1989) (per curiam); United States v. Vanwort, 887 F.2d 375, 382-83 (2d Cir.1989) (applying Gomez and holding that magistrate judge’s jury selection does not necessitate reversal of verdict when defendant failed to object), cert. denied, 495 U.S. 906, 110 S.Ct. 1927, 109 L.Ed.2d 290 (1990); United States v. Mang Sun Wong, 884 F.2d 1537, 1544-46 (2d Cir.1989) (order on petition for rehearing) (same), cert. denied, 493 U.S. 1082, 110 S.Ct. 1140, 107 L.Ed.2d 1045 (1990); see also Government of the Virgin Islands v. Williams, 892 F.2d 305, 309-12 (3d Cir.1989) (failure to object constitutes consent to reference), cert. denied, 495 U.S. 949, 110 S.Ct. 2211, 109 L.Ed.2d 537 (1990); United States v. Ford, 824 F.2d 1430, 1438-39 (5th Cir.1987) (failure to object to magistrate’s jury selection constitutes waiver of error); cf. United States v. Rivera-Sola, 713 F.2d 866, 874 (1st Cir.1983) (because defendant failed to object to magistrate’s jury selection “we review only for plain error”). Any error below was a procedural lapse, not a jurisdictional failing. Archie v. Christian, 808 F.2d 1132, 1134-35 (5th Cir.1987) (en banc).8
*1368III. De Novo Review
On August 18, 1987, the magistrate judge held an evidentiary hearing, which was recorded. On September 16, he recommended that Clark’s suit be dismissed. Clark objected to this recommendation, but on December 31 the district court dismissed the action. The dismissal order states that the court “made a de novo review” of the case, R. Yol. I, Tab 49, at 2, but the recording of the evidentiary hearing had not yet been transcribed.
“When objections are made to the magistrate’s factual findings based on conflicting testimony or evidence, both § 636(b)(1) and Article III of the United States Constitution require de novo review.” Gee v. Estes, 829 F.2d 1005, 1008 (10th Cir.1987) (citation omitted). “In conducting this review, the district court must, at a minimum, listen to a tape recording or read a transcript of the evidentiary hearing.” Id. at 1009.
Gee was decided three months before the district court dismissed Clark’s action. We presume that the district court knew the relevant law, United States v. Lowden, 905 F.2d 1448, 1449 n. 1 (10th Cir.), cert. denied, — U.S. —, 111 S.Ct. 206, 112 L.Ed.2d 166 (1990), so the court’s statement that it conducted a de novo review must be taken to mean that it listened to the tape recording of the hearing before it dismissed Clark’s suit. See Andrews v. Deland, 943 F.2d 1162, 1171 (10th Cir.1991) (“We will not look behind a district court’s express statement that it engaged in a de novo review of the record.”), cert. denied, — U.S. —, 112 S.Ct. 1213, 117 L.Ed.2d 451 (1992). Indeed, because of the expense and delay9 of transcription, district courts commonly listen to a tape rather than await a transcript.
Branch v. Martin, 886 F.2d 1043 (8th Cir.1989), which remanded in similar circumstances, is distinguishable. As here, the district court adopted the magistrate judge’s recommendations before the transcript of a recorded hearing was prepared. As here, the district court stated that it had conducted a de novo review, but did not say anything about listening to the tape. Id. at 1046; see also Moran v. Morris, 665 F.2d 900, 901-02 (9th Cir.1981) (court of appeals remanded for further review of tape-recorded proceedings before magistrate judge after district court adopted magistrate judge’s recommendations the day they were issued). The important distinction is that Branch announced for the Eight Circuit the rule we adopted in Gee. The district court in Branch did not have the benefit of that decision, but the court below was aware of Gee. The doubts the Eight Circuit held about the breadth of that district court’s review would be unfounded here.
IV. Merits
On the merits of Clark’s claims, we agree with the decision of the district court. Accordingly, the judgment is AFFIRMED.
. Clark's claims regarding the denial of medical treatment while in jail and his challenge to the jail magazine policy were consolidated with his excessive force claims.
. Section 636(b)(1)(A) provides in pertinent part as follows:
[A] judge may designate a magistrate to hear and determine any pretrial matter pending before the court, except a motion for injunc-tive relief, for judgment on the pleadings, for summary judgment, to dismiss or quash an indictment or information made by the defendant, to suppress evidence in a criminal case, to dismiss or to permit maintenance of a class action, to dismiss for failure to state a claim upon which relief can be granted, and to involuntarily dismiss an action.
28 U.S.C. § 636(b)(1)(A).
. Section 636(b)(1)(B) provides as follows:
[A] judge may also designate a magistrate to conduct hearings, including evidentiary hearings, and to submit to a judge of the court proposed findings of fact and recommendations for the disposition, by a judge of the court, of any motion excepted in subpara-graph (A), of applications for post-trial relief made by individuals convicted of criminal offenses and of prisoner petitions challenging conditions of confinement.
28 U.S.C. § 636(b)(1)(B).
. Section 636(c)(2) explains the consent requirement more fully:
If a magistrate is designated to exercise civil jurisdiction under paragraph (1) of this subsection, the clerk of the court shall, at the time the action is filed, notify the parties of the availability of a magistrate to exercise such jurisdiction. The decision of the parties shall be communicated to the clerk of the court. Thereafter, either the district court judge or the magistrate may again advise the parties of the availability of the magistrate, but in so doing, shall also advise the parties that they are free to withhold consent without adverse substantive consequences. Rules of court for the reference of civil matters to magistrate shall include procedures to protect the voluntariness of the parties’ consent.
28 U.S.C. § 636(c)(2).
. The dissent argues that section 636(b)(3) does not confer authority to refer to a magistrate a section 1983 action that does not challenge a condition of confinement, absent the plaintiffs express consent. We disagree. Peretz permits referral to the magistrate of felony trial jury voir dire where the parties consent or where the defendant raises no objection. See Peretz, 111 S.Ct. at 2667-68 (Court approves the reasoning of circuit court cases holding that “the rationale of [Gomez] does not apply when the defendant has not objected to the magistrate’s conduct of the voir dire."); see also id. at 2669 ("a defendant has no constitutional right to have an Article III judge preside at jury selection if the defendant has raised no objection to the judge’s absence."). Both the presence of consent, and the lack of an objection, provide independent bases for the Court’s conclusion that voir dire by a magistrate violated neither the Federal Magistrate's Act nor Article III. See United States v. Martinez-Torres, 944 F.2d 51 (1st Cir.1991) (en banc); United States v. Amoldt, 947 F.2d 1120, 1123 (4th Cir.1991), cert. den., — U.S. —, 112 S.Ct. 1666, 118 L.Ed.2d 387 (1992).
. The Court stated:
Equally basic is a defendant's right to have all critical stages of a criminal trial conducted by a person with jurisdiction to preside. Thus harmless-error analysis does not apply in a felony case in which, despite the defendant’s *1367objection and without any meaningful review by a district judge, an officer exceeds his jurisdiction by selecting a jury.
Gomez, 490 U.S. at 876, 109 S.Ct. at 2248.
. The Supreme Court did, however, state in dicta:
We agree with the view of the majority of Circuit Judges who have considered this issue, both before and after our decision in Gomez, that permitting a magistrate to conduct the voir dire in a felony trial when the defendant raises no objection is entirely faithful to the congressional purpose in enacting and amending the Federal Magistrates Act.
111 S.Ct. at 2671.
. We note that a panel of our court, relying, as it must, on the previous panel opinion in Clark, stated in dictum that "[t]he failure to object does not waive issues concerning the magistrate’s jurisdiction.” Moore v. United States, 950 F.2d 656, 659 n. 7 (10th Cir.1991). That dictum does not bind us, however, in view of our withdrawal of the previous panel opinion in Clark, which Moore cited, and the substitution of this opinion.
. The transcript in this case was not prepared until almost 14 months after the hearing was held. See R.Supp. Vol. II.