Defendant contends that his convictions must be set aside for several reasons. First of all, he contends that his conviction is constitutionally invalid because the jury was not required to apply a statewide contemporary community standard in determining whether the materials at issue in this case were obscene. He also assigns error to the exclusion of: (1) evidence as to the availability of similar materials in the community; (2) evidence as to the results of a public opinion survey; and (3) expert opinion testimony upon the issue of the obscenity of the materials. In addition, he challenges the sufficiency of the State’s evidence, assigns error to portions of the trial court’s instructions to the jury, and contests the constitutionality of G.S. 14-190.1 on a number of grounds. For the following reasons, we hold that defendant received a fair trial, free of prejudicial error.
We begin our analysis by stating that which is firmly established: obscene material receives no protection under the First Amendment to the United States Constitution. Miller v. California, 413 U.S. 15, 37 L.Ed. 2d 419, 93 S.Ct. 2607, reh'g denied, 414 U.S. 881, 38 L.Ed. 2d 128, 94 S.Ct. 26 (1973); Roth v. United States, 354 U.S. 476, 1 L.Ed. 2d 1498, 77 S.Ct. 1304, reh’g denied, 355 U.S. 852, 2 L.Ed. 2d 60, 78 S.Ct. 8 (1957). “It has been well observed that such utterances are no essential part of any exposition of ideas, and are of such slight social value as a step to truth *572that any benefit that may be derived from them is clearly outweighed by the social interest in order and morality.” Chaplinsky v. New Hampshire, 315 U.S. 568, 572, 86 L.Ed. 2d 1031, 1035, 62 S.Ct. 766, 769 (1942). States, therefore, are free to enact criminal statutes prohibiting the dissemination of obscene material, provided that specified guidelines are followed so that protected speech is not also prohibited. See Miller, supra.
By ? his first assignment of error, defendant contends that G.S. 14-190.1 is constitutionally infirm because it does not require the jury to apply statewide community standards in determining whether materials are obscene. He also contends that his conviction is invalid because the trial court failed to instruct the jury to apply a statewide standard or to define for the jury the relevant community whose standards were to be applied. We reject his contentions.
G.S. 14-190.1(b) provides that material is obscene if:
(1) The material depicts or describes in a patently offensive way sexual conduct specifically defined by subsection (c) of this section; and
(2) The average person applying contemporary community standards relating to the depiction or description of sexual matters would find that the material taken as a whole appeals to the prurient interest in sex; and
(3) The material lacks serious literary, artistic, political, or scientific value; and
(4) The material as used is not protected or privileged under the Constitution of the United States or the Constitution of North Carolina.
G.S. 14-190.1(c) defines sexual conduct as:
(1) Vaginal, anal, or oral intercourse, whether actual or simulated, normal or perverted; or
(2) Masturbation, excretory functions, or lewd exhibition of uncovered genitals; or
*573(3) An act or condition that depicts torture, physical restraint by being fettered or bound, or flagellation of or by a nude person or a person clad in undergarments or in revealing or bizarre costume.
The language used in this statute closely follows the three-pronged test set forth by the United States Supreme Court in Miller v. California, supra:
The basic guidelines for the trier of fact must be: (a) whether “the average person, applying contemporary community standards” would find that the work, taken as a whole, appeals to the prurient interest, [citations omitted]; (b) whether the work depicts or describes, in a patently offensive way, sexual conduct specifically defined by the applicable state law; and (c) whether the work, taken as a whole, lacks serious literary, artistic, political, or scientific value.
Id. at 24, 37 L.Ed. 2d at 431, 93 S.Ct. at 2615. As recently as the present term, the Supreme Court has reemphasized that contemporary community standards are to be applied to the first two prongs, while the third prong is to be examined according to the reasonable person standard. See Pope v. Illinois, 481 U.S. —, 95 L.Ed. 2d 439, 107 S.Ct. 1918 (1987).
In Miller, the Court held that the use of national standards to determine whether material is obscene is not a constitutional requirement, and that states could properly employ statewide contemporary community standards. Miller, however, does not require the use of statewide standards. In Jenkins v. Georgia, 418 U.S. 153, 41 L.Ed. 2d 642, 94 S.Ct. 2750 (1974), the trial court instructed the jury to apply “community standards” without defining the geographical limits of “community.” The Supreme Court approved the instructions, stating that:
Miller held that it was constitutionally permissible to permit juries to rely on the understanding of the community from which they came as to contemporary community standards, and the States have considerable latitude in framing statutes under this element of the Miller decision. A State may choose to define an obscenity offense in terms of “contemporary community standards” as defined in Miller without further specification ... or it may choose to define the standards in *574more precise geographic terms, as was done by California in Miller.
Id. at 157, 41 L.Ed. 2d at 648, 94 S.Ct. at 2753. See also Hamling v. United States, 418 U.S. 87, 41 L.Ed. 2d 590, 94 S.Ct. 2887, reh'g denied, 419 U.S. 885, 42 L.Ed. 2d 129, 95 S.Ct. 157 (1974). Our General Assembly chose not to define “community” in precise geographic terms when it enacted G.S. 14-190.1. In the absence of a precise statutory specification of “community,” the trial judge properly declined to judicially restrict or expand that term, permitting the jurors to apply the standards of the community from which they came in much the same manner as they would determine “the propensities of a ‘reasonable’ person in other areas of the law.” Id. at 104-105, 41 L.Ed. 2d at 613, 94 S.Ct. at 2901. Accordingly, we hold that neither G.S. 14-190.1 nor the judge’s instructions in this case contravene the Constitution of the United States by failing to specify what is meant by “community.”
Defendant argues, however, that the use of a statewide standard is required by Article I, § 19 of the Constitution of North Carolina, which provides in part that “[n]o person shall be taken, imprisoned, or disseized of his freehold, liberties, or privileges ... or in any manner deprived of his life, liberty, or property, but by the law of the land. No person shall be denied equal protection of the laws. . . .” Defendant argues that use of any standard smaller than a statewide one is impermissible because such a standard would make it illegal in some parts of this State to do that which is legal in other parts of the State.
G.S. 14-190.1 makes it a criminal offense in North Carolina to disseminate obscenity. This is so throughout the State. It is true that the application of standards of a community smaller than statewide may result in the possibility that material considered obscene in some areas of the State will not be considered obscene in other areas. This possibility does not, however, render the statute unconstitutional. In Miller, supra, the Supreme Court held that the federal Constitution does not require materials to be judged in the light of hypothetical national standards, saying that it is unrealistic and not constitutionally required that “the people of Maine or Mississippi accept public depiction of conduct found tolerable in Las Vegas, or New York City.” Id. at 32, 37 L.Ed. 2d at 435, 93 S.Ct. at 2619. In Hamling, supra, the Court held that a *575juror sitting in obscenity cases is permitted “to draw on knowledge of the community or vicinage from which he comes in deciding what conclusion ‘the average person, applying contemporary community standards’ would reach in a given case.” Id. at 105, 41 L.Ed. 2d at 613, 94 S.Ct. at 2901.
The fact that distributors of allegedly obscene materials may be subjected to varying community standards in the various federal judicial districts into which they transmit the materials does not render a federal statute unconstitutional because of the failure of application of uniform national standards of obscenity.
Id. at 106, 41 L.Ed. 2d at 614, 94 S.Ct. at 2902. In Jenkins, supra, the Court held that in state obscenity cases, jurors need not be instructed “to apply the standards of a hypothetical statewide community.” Id. at 157, 41 L.Ed. 2d at 648, 94 S.Ct. at 2753.
We believe that the reasoning of the United States Supreme Court is applicable as well to the “equal protection of the laws” clause of our State Constitution. Ours is a large and diverse State, and it is unrealistic to expect to find that the same standards exist throughout the State or that the residents of one part of the State would have knowledge of the community standards held in another area. Thus we hold that permitting jurors to apply the standards of the community from which they come, rather than requiring the application of a uniform statewide standard of obscenity, does not violate the equal protection clause of the North Carolina Constitution.
Defendant next argues that the trial court erred by preventing the jury from hearing certain proffered evidence. Specifically, defendant assigns error to the exclusion of testimony by Dr. Charles Winick, a psychologist, sex therapist, and public opinion researcher, concerning the results of a statewide survey which he conducted for the defense; the exclusion of opinion testimony by Dr. Terry Cole, a speech communications professor at Appalachian State University, as to whether the materials at issue in this case were obscene; and the exclusion of testimony by private investigator Jan Frankowitz as to the availability of similar material in the community. We hold that the trial court committed no error prejudicial to defendant by excluding the testimony of either expert witness nor of Ms. Frankowitz.
*576The United States Supreme Court has held that there is no constitutional need for expert testimony that the subject materials are obscene once the materials have been placed in evidence, as the materials themselves are the best evidence of what they represent. Paris Adult Theatre I v. Slaton, 413 U.S. 49, 37 L.Ed. 2d 446, 93 S.Ct. 2628, reh’g denied, 414 U.S. 881, 38 L.Ed. 2d 128, 94 S.Ct. 27 (1973). The defense is free, however, to introduce expert testimony as to the obscenity of the materials. Kaplan v. California, 413 U.S. 115, 37 L.Ed. 2d 492, 93 S.Ct. 2680, reh’g denied, 414 U.S. 883, 38 L.Ed. 2d 131, 94 S.Ct. 28 (1973). While it is established that expert testimony is admissible in obscenity trials, the trial court retains “wide discretion in its determination to admit and exclude evidence, and this is particularly true in the case of expert testimony.” Hamling, supra at 108, 41 L.Ed. 2d at 615, 94 S.Ct. at 2903. Once the expert witness demonstrates “knowledge, skill, experience, training or education” as required by G.S. 8C-1, Rule 702, “the test of admissibility is helpfulness.” Brandis, North Carolina Evidence § 132 (Cum. Supp. 1986). As explained in State v. Knox, 78 N.C. App. 493, 337 S.E. 2d 154 (1985), “[t]he test for admissibility is whether the jury can receive ‘appreciable help’ from the expert witness. 7 J. Wigmore, Evidence Sec. 1923 at 29 (Chadbourn rev. 1978). Applying this test requires balancing the probative value of the testimony against its potential for prejudice, confusion or undue delay.” Id. at 495, 337 S.E. 2d at 156.
Defendant first argues that the trial court erred by preventing Dr. Winick from testifying as to results of a survey he conducted in North Carolina. That survey, conducted among 400 adults in 41 counties, contained the following questions pertinent to defendant’s argument:
2. In your opinion, have standards changed in recent years, so that depictions of nudity and sex are more acceptable or less acceptable in movies, video cassettes, publications, and other materials depicting nudity and sex and available only to adults, but not to children?
3. Do you agree or disagree that adults who want to, have the right to obtain and see movies, video cassettes, publications and other materials depicting nudity and sex and which are available only to adults, but not to children?
*5774. Do you agree or disagree that adults who want to, have the right to patronize and make purchases at bookstores where publications and other materials depicting nudity and sex are available only to adults, but not to children?
5. Do you agree or disagree that adults that want to, have the right to patronize theatres where movies presenting nudity and sex are available only to adults, but not to children?
6. Do you think it is alright or not alright, for adults who wish to do so, to obtain and see in the privacy of their homes, movies, video cassettes, publications and other materials depicting nudity and sex, which are available only to adults and not to children?
7. We have used the words nudity and sex in the preceding questions. What we mean by these words includes exposure of the genitals and every kind of sexual activity, no matter how graphically depicted. Is that what you understood we meant, or did you think we meant something else?
After conducting a voir dire, the court permitted Dr. Winick to testify concerning the responses to questions 2 and 7 of the survey but excluded any testimony relating to questions 3 through 6. Defendant argues that this exclusion was improper because it removed from the jury’s consideration information which would have been valuable in assisting it in determining community standards. We find no error in the trial court’s ruling.
The questions excluded by the court have absolutely no relevance to what the community considers obscene. Questions 3, 4 and 5 are general opinion questions as to what adults “have the right” to obtain and view; they have little, if any, probative value on the issue of whether “the average person applying contemporary community standards” would find that the subject magazines are patently offensive or appeal to the prurient interest in sex. We agree with the analysis of the Georgia Court of Appeals in Flynt v. State, 153 Ga. App. 232, 264 S.E. 2d 669, cert. denied, 449 U.S. 888, 66 L.Ed. 2d 114, 101 S.Ct. 245 (1980):
One may be of the opinion that adults have the right to obtain and view materials depicting “nudity and sex” although they would themselves regard the material as exceeding the *578bounds of “contemporary community standards” and as patently offensive. The survey asked no more than whether the respondents objected to the dissemination of materials depicting nudity and sex to willing adults, not whether they regarded material such as that depicted in appellant’s magazines as obscene in themselves.
Id. at 233, 264 S.E. 2d at 672.
Similarly, question 6 did not address the issue of the obscenity of any material, but only the question of whether adults had a right to view, in the privacy of their homes, materials depicting nudity and sex. However, G.S. 14-190.1 prohibits only the intentional dissemination of obscenity, not the private possession thereof. The First and Fourteenth Amendments prohibit making mere private possession of obscene material a crime. Stanley v. Georgia, 394 U.S. 557, 22 L.Ed. 2d 542, 89 S.Ct. 1243 (1969). Therefore, this question has no probative value regarding the question of contemporary community standards, or even regarding the crime with which defendant was charged. We find no abuse of discretion by the trial court in excluding evidence of these survey questions.
Defendant also assigns error to the court’s exclusion of expert testimony by Dr. Terry Cole as to whether in his opinion, the magazines in question depict sexual conduct in a patently offensive way, whether they appeal only to a prurient interest, and whether they have serious literary, artistic, political, or scientific value. Defendant’s proffer of evidence reveals that Dr. Cole would have testified, in summary, that due to the fact that the magazines were offered for sale at places frequented only by adults who chose to do so, he was of the opinion that the magazines are not patently offensive. He would also have testified that the magazines have scientific value because of their use in speech classes when discussing obscenity, as well as in marriage counseling and sex therapy, and that they have political value because they contribute to the public debate concerning obscenity and sexuality. We hold that the trial judge did not commit reversible error by excluding Dr. Cole’s testimony.
The issues before the jury were whether, under contemporary community standards, the magazines are patently offensive and appeal to prurient interest and whether they have literary, *579artistic, political, or scientific value. The inquiry put to Dr. Cole with respect to whether or not the material is patently offensive was not premised upon his knowledge of contemporary community standards, and was therefore irrelevant to, and could not have assisted the jurors in deciding, the issues in the case. See State v. Knox, supra. Neither the fact that the materials might be used in teaching classes on obscenity and in classroom discussions with respect thereto, nor the fact that the materials are relevant to the public debate on the issue of obscenity establish that the materials have serious scientific or political value. Under such circular reasoning, nothing could ever be found obscene because its value derives from the fact that it may be obscene. Such a result was certainly not intended by the Supreme Court when it established the Miller test. We find no error in the exclusion of this testimony.
Dr. Cole also testified on voir dire that the materials at issue in this case have scientific value in marriage and sex counseling and do not appeal to a prurient interest in sex. We question whether such testimony is within the expertise of Dr. Cole, who was tendered and admitted as an expert in “speech communication in the context of public communication.” However, even assuming that the trial court should have permitted Dr. Cole to state these opinions before the jury, defendant has suffered no prejudice by their exclusion because the same evidence was subsequently placed before the jury through the testimony of Dr. Winick. “[A] litigant is not harmed by the exclusion of testimony, when the same, or substantially the same, testimony is subsequently admitted.” Powell v. Daniel, 236 N.C. 489, 492, 73 S.E. 2d 143, 145 (1952).
Defendant also assigns error to the trial court’s refusal to allow Jan Frankowitz to testify before the jury concerning her purchase of two magazines, described as similar to the materials at issue, from a “Pantry” convenience store in Shelby. Defendant argues that this evidence was probative of, and therefore relevant to, the issue of the “contemporary community standard with respect to patent offensiveness and prurient appeal of sexually explicit materials.” We disagree. Availability of similar material alone means nothing more than that other persons are engaged in similar activities. Hamling, supra„• Flynt, supra. Evidence of mere availability of similar materials is not by itself sufficiently pro*580bative of community standards to be admissible in the absence of proof that the material enjoys a reasonable degree of community acceptance. See United States v. Manarite, 448 F. 2d 583 (2d Cir.), cert. denied, 404 U.S. 947, 30 L.Ed. 2d 264, 92 S.Ct. 298 (1971). Defendant argues that the availability of the magazines bought by Ms. Frankowitz in a neighborhood convenience store indicates community acceptance. On the contrary, this indicates only availability, not acceptance. We find no error in the trial court’s exclusion of this evidence.
Defendant next assigns as error the trial court’s denial of his motions to dismiss and for judgment notwithstanding the verdict. Citing Smith v. California, 361 U.S. 147, 4 L.Ed. 2d 205, 80 S.Ct. 215 (1959), reh’g denied, 361 U.S. 950, 4 L.Ed. 2d 383, 80 S.Ct. 399 (1960), defendant accurately argues that dissemination of obscenity cannot be a strict liability crime, and that G.S. 14190.1(a) requires proof of both intent and guilty knowledge. See Cinema I Video, Inc. v. Thornburg, 83 N.C. App. 544, 351 S.E. 2d 305 (1986), aff'd, 320 N.C. 485, 358 S.E. 2d 383 (1987), citing State v. Bryant and State v. Floyd, 16 N.C. App. 456, 192 S.E. 2d 693 (1972), appeal dismissed and cert. denied, 282 N.C. 583, 193 S.E. 2d 747, vacated and remanded, 413 U.S. 913, 37 L.Ed. 2d 1036, 93 S.Ct. 3065, reaffirmed, 20 N.C. App. 223, 201 S.E. 2d 211 (1973), affirmed, 285 N.C. 27, 203 S.E. 2d 27, cert. denied, 419 U.S. 974, 42 L.Ed. 2d 188, 95 S.Ct. 238 (1974). Defendant’s contention that the State presented insufficient evidence to show defendant’s guilty knowledge, however, is without merit. At trial, Sgt. McKinney testified that defendant told him that the materials for sale in the bookstore were illegal. In addition, there was testimony tending to show that defendant was the store manager. Treating this evidence in the light most favorable to the State, as we must, State v. Earnhardt, 307 N.C. 62, 296 S.E. 2d 649 (1982), we hold that it is sufficient to permit a reasonable inference that defendant knew the nature and content of the materials he sold to Sgt. McKinney. The evidence was, therefore, sufficient to withstand defendant’s motions.
By the same argument in his brief, defendant assigns error to the trial court’s instructions to the jury on the issue of defendant’s intent and guilty knowledge. Defendant contends that the trial court’s denial of numerous requests for jury instructions resulted in a failure by the court to explain to the jury “the ex*581planatory and guiding principles needed to properly apply the complex principles of law involved to the facts of this case.” We disagree.
A judge’s charge to the jury is sufficient when it fully instructs the jury on all substantive areas of the case and adequately defines and applies the law thereto. State v. McNeil, 47 N.C. App. 30, 266 S.E. 2d 824, cert. denied and appeal dismissed, 301 N.C. 102, 273 S.E. 2d 306 (1980), cert. denied, 450 U.S. 915, 67 L.Ed. 2d 339, 101 S.Ct. 1356 (1981). Although a judge is required to give such instructions as may be specifically requested, when correct and supported by the evidence, the instructions need not be in the exact language requested; it is sufficient if the court gives the instructions in substance. State v. Davis, 291 N.C. 1, 229 S.E. 2d 285 (1976); State v. Travatello, 24 N.C. App. 511, 211 S.E. 2d 467 (1975). The court’s instructions must be read as a whole and in context, and individual portions will not be held prejudicial if the charge as a whole is correct. State v. Craig and State v. Anthony, 308 N.C. 446, 302 S.E. 2d 740, cert. denied, 464 U.S. 908, 78 L.Ed. 2d 247, 104 S.Ct. 263 (1983).
In the present case, the trial judge properly instructed the jurors that, to convict defendant, they must find beyond a reasonable doubt that he intentionally disseminated material which, when viewed in its entirety, is obscene. The judge instructed the jury that the State bore the burden of proving beyond a reasonable doubt that defendant “knew the content, character and nature of the magazines as a whole that he sold. . . .” The instructions given were a sufficient statement of the law with respect to defendant’s intent and guilty knowledge. This assignment of error is overruled.
We have also reviewed defendant’s other assignments of error with respect to the court’s instructions to the jury. We conclude that the instructions, when construed as a whole and in context, were correct.
Finally, defendant contends that the trial court should have dismissed the charges because G.S. 14-190.1 is unconstitutional. He bases his constitutional challenge to the statute upon five asserted shortcomings: (1) that the statute fails to include scienter as an element of the proscribed conduct; (2) that it fails to provide for a prompt judicial determination of obscenity; (3) that it is *582overbroad in that it does not specify that the unlawful dissemination of obscenity is limited to that dissemination which occurs in a public place; (4) that it is overbroad in its definition of “sexual conduct”; and (5) that it fails to require that material be “taken as a whole” in the determination of the material’s literary, artistic, political, or scientific value. Each of these issues has previously been decided adversely to defendant. Cinema I Video v. Thornburg, supra. We find no error in the denial of his motion to dismiss based upon the asserted unconstitutionality of the statute.
In conclusion, we hold that defendant received a fair trial, free from prejudicial error.
No error.
Judge COZORT concurs. Judge BECTON concurs in part and dissents in part.