microcassette recorder she carried. Investigators, who at first found only 22 minutes recorded on one side of the tape, sent it to Ginsberg for enhancement and transcription. He discovered an additional 22 minutes on the second side containing valuable cl ues that further identified the killer. With such damning evidence, the suspect pled guilty and, at this writing, is awaiting sentencing. Though the full contents of the tape have never been disclosed, the released portions showed that Weinstein used her skills as a teacher to reason with her abductor, and when that failed she called on God before crying and begging for her life. The tape ran out before the murder, but Ginsberg, who calls Weinstein "an angel:' heard as much as he could bear. Other cases, Ginsberg says, are less emotional but m ore technically challenging. During the now-infamous 1993 standoff at the Branch Davidians' complex in Waco, FBI agents slipped a bugging device into the cult's compound along with some foodstuffs. The transmitter was active during the "seige" in which ag ents tried to force the Davidians out with tear gas and then rushed the building with tanks, only to see the whole place go up in flames. The Justice Department hoped that the recordings made from the bug could shed light on what happened and help prosecu te the survivors. Ginsberg was asked to clarify the tapes and make transcripts, but when he heard them he was taken aback. "These tapes had people talking through gas masks. There was screaming, gunfire, tanks advancing, and alot of confusion. Add to this that the voices were muffled because they were not on top of the device, which has a very low-power transmitter to begin with. These were some of the noisiest tapes I've ever heard."

microcassette recorder she carried. Investigators, who at first found only 22 minutes recorded on one side of the tape, sent it to Ginsberg for enhancement and transcription. He discovered an additional 22 minutes on the second side containing valuable cl ues that further identified the killer. With such damning evidence, the suspect pled guilty and, at this writing, is awaiting sentencing. Though the full contents of the tape have never been disclosed, the released portions showed that Weinstein used her skills as a teacher to reason with her abductor, and when that failed she called on God before crying and begging for her life. The tape ran out before the murder, but Ginsberg, who calls Weinstein "an angel:' heard as much as he could bear. Other cases, Ginsberg says, are less emotional but m ore technically challenging. During the now-infamous 1993 standoff at the Branch Davidians' complex in Waco, FBI agents slipped a bugging device into the cult's compound along with some foodstuffs. The transmitter was active during the "seige" in which ag ents tried to force the Davidians out with tear gas and then rushed the building with tanks, only to see the whole place go up in flames. The Justice Department hoped that the recordings made from the bug could shed light on what happened and help prosecu te the survivors. Ginsberg was asked to clarify the tapes and make transcripts, but when he heard them he was taken aback. "These tapes had people talking through gas masks. There was screaming, gunfire, tanks advancing, and alot of confusion. Add to this that the voices were muffled because they were not on top of the device, which has a very low-power transmitter to begin with. These were some of the noisiest tapes I've ever heard."

He keeps tape decks in a half-dozen different formats, including an unusual high-end microcassette deck from a company called Daniel Technology and a tiny "spy" recorder, a Nagra open-reel portable that measures just 4 x 6 x 1 inches and uses Zinch reels of tape only 0.15 inch wide. There are even a couple of Dictaphone "loggers" -- giant multitrack tape decks used by police for tracking emergency calls and by brokerage firms to monitor securities transactions. They ca n record sixty tracks simultaneously on a reel of i-inch-wide tape. Other tools of Ginsberg's trade include a large selection of bandpass and notch filters that are helpful for zeroing in on the voice frequency range -- approximately 300 Hz to 3 IrHz -- o r eliminating sounds at certain frequencies. There's a compression/expansion amplifier used to even things out when the voices on a tape are recorded at different volume levels, a processor that restores the proper pitch to voices if Ginsberg needs to spe ed up or slow down a tape to clarify it, a "black box" that decodes recorded telephone and calling-card touch-tones, and a small, innocuous tin can containing iron particles in a liquid suspension. Dip a section of tape into the harmless solution, and you can actually see the magnetic tracks, which can determine, for example, whether a tape was recorded in mono or stereo. At the opposite end of the spectrum are Ginsberg's high-tech digital toys. He uses a fast-Fourier-transform (FFT) spectrum analyzer to visually examine the frequency content of a tape and isolate noise elements from the voices. Likewise, his digital wave-form oscilloscope can be used to see the sonic "signatures" left on a tape by minuscule spikes that occur whenever a recording is started or stopped. And his Pentium computer runs a sophisticated, $15,000 custom software package that can actually discriminate between voices and interference and remove the noise digitally. So what kind of stereo system does Ginsberg listen to for fun? Well, his home entertainment syst em consists of an aging receiver, a CD player, bookshelf speakers, and a rugged Fisher-Price kiddie radio that keeps him company in his solitary work. But this is one golden ear who makes no apologies. Paul Ginsberg lives his passion for sound every day i n a way most audiophiles can only dream about. And though you won't find him auditioning home-theater components any time soon, he does apply his most critical faculties when shopping for an automobile. You see, the audio detective spends a lot of time in his car, shuttling evidence tapes back and forth. "s because it has a quiet interior and an excellent sound system," he notes, adding, "I only wish it had a head phone jack."