Piotr (or Pjotr) Zak is the name of a fictional Polish composer whose alleged composition Mobile for Tape and Percussion was broadcast twice on the BBC Third Programme on 5 June 1961 in a performance supposedly played by "Claude Tessier" and "Anton Schmidt".
Further down the scale from Noble's overall pan (leavened with some extremely faint praise), the Daily Telegraph's′ critic Donald Mitchell called the performance "wholly unrewarding", adding that Zak exploited the percussion with only limited enterprise and his tape emitted a succession of whistles, rattles and punctured sighs that proclaimed, all too shamelessly, their non-musical origins....There was nothing, one felt, to "understand" here.
[7] Rollo Myers, writing in the Listener, was harsher still, accurately identifying the piece as a farce d'atelier (studio prank) with "no possible claim to be considered as music", and characterising the BBC's broadcast of such a thing "a serious error of judgment".
the tape exploits the full range of the aural spectrum, controlled by strictly measurable quantities—frequency ratios, velocity graphs and decibel indexes"—all this to describe what seemed to me to be a series of the more unpleasant kinds of kitchen noises, accompanied by bangs and thumps, hisses, shrieks and whistles.
[8] He concluded with praise for the other works on the programme, by Webern, Nono, Petrassi, and "the always satisfying Serenade in B flat for thirteen wind instruments by Mozart—which may have been missed by the many listeners who, I am sure, switched off their sets for the repeat performance of the Zak".
By striking randomly and with deliberate senselessness at a collection of percussion instruments, the two (as "Tessier" and "Schmidt") had produced a strenuously meaningless twelve-minute "work" of superficially "avant-garde" character; this was completed by the addition of a selection of human whistling sounds (evidently meant to represent the "tape"), and with the resulting chaos being edited into some kind of whole by BBC technicians.
[11] Revealing the true nature of the work was itself apparently part of the publicity for the BBC broadcast of a radio documentary, The Strange Case of Piotr Zak, first aired on 13 August 1961, in which Keller discussed his hoax with music critics Jeremy Noble and Donald Mitchell.