; and (3) after providing notice and an opportunity to respond, and upon good cause shown, the Copyright Claims Board may apply an adverse inference with respect to disputed facts against a party who has failed to timely provide discovery materials in response to a proper request for materials that could be relevant to such facts. (o) Evidence The Copyright Claims Board may consider the following types of evidence in a proceeding, and such evidence may be admitted without application of formal rules of evidence: (1) Documentary and other nontestimonial evidence that is relevant to the claims, counterclaims, or defenses in the proceeding. (2) Testimonial evidence, submitted under penalty of perjury in written form or in accordance with subsection (p), limited to statements of the parties and nonexpert witnesses, that is relevant to the claims, counterclaims, and defenses in a proceeding, except that, in exceptional cases, expert witness testimony or other types of testimony may be permitted by the Copyright Claims Board for good cause shown. (p) Hearings The Copyright Claims Board may conduct a hearing to receive oral presentations on issues of fact or law from parties and witnesses to a proceeding, including oral testimony, subject to the following: (1) Any such hearing shall be attended by not fewer than two of the Copyright Claims Officers. (2) The hearing shall be noted upon the record of the proceeding and, subject to paragraph (3), may be recorded or transcribed as deemed necessary by the Copyright Claims Board. (3) A recording or transcript of the hearing shall be made available to any Copyright Claims Officer who is not in attendance. (q) Voluntary dismissal (1) By claimant Upon the written request of a claimant that is received before a respondent files a response to the claim in a proceeding, the Copyright Claims Board shall dismiss the proceeding, or a claim or respondent, as requested, without prejudice. (2) By counterclaimant Upon written request of a counterclaimant that is received before a claimant