Just resending this post as for some reason the first email appeared to only
go to Paul rather than the ARSCLIST .
----- Original Message -----
From: "Tim Gillett" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, July 08, 2017 10:37 AM
Subject: Re: [ARSCLIST] Unexplained sound on oral history cassette
> Thanks for the audio example of the press Paul. The press sound very
> different from the sound on the recording in a number of ways.
> But also the voice recording contains considerable room reverberation.
> The creaking sound does not. How likely would it be for the microphone to
> be placed right on top of such a printing press, while it was operating
> (!), while recording an interview with someone on the distant side of the
> ----- Original Message -----
> From: "Paul Jackson" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Saturday, July 08, 2017 6:28 AM
> Subject: Re: [ARSCLIST] Unexplained sound on oral history cassette
>> Everyone has made good argumentsthat the sound is from the tape
>> processing noise. But having worked with printing machines I'm a bit more
>> inclined to believe it's a printer in the background.
>> Here is the actual sound of a Heidelberg Platen Printing Press; why I
>> think it is this in the background, perhaps behind an open door in
>> another room. http://www.workwithsounds.eu/sound/heidelberg-platen-press/
>> --Paul Jackson
>> On 7/7/2017 2:53 PM, Tim Gillett wrote:
>>> I dont think the creak sound emanates from the room but from the
>>> recorder. It carries very little room reverb so must be very close to
>>> the mic, whereas the speaker's voice carries lots of room reverb,
>>> suggesting a distant mic placement from him.
>>> The frequency of repetition of the "creak" seems roughly the same as a
>>> complete rotation of the supply tape pack around the beginning of a tape
>>> side, so perhaps a cyclic binding of the supply tape pack at each
>>> The creak sounds mechanical. It could be related to the primitive
>>> tape auto stop in many cheap cassette recorders which consisted of a
>>> small "finger" pressing onto the tape through the cassette's small
>>> window left of centre. End of the tape greatly increased back tension
>>> pushing the finger back, engaging a flywheel powered cog or cam which
>>> mechanically tripped the stop function. Often even at end of tape, the
>>> lever didnt quite fully engage into the cam or cog and instead "bounced"
>>> on it in a chattering fashion, which may be the noise we are hearing: a
>>> false or partial triggering due to the increased back tension. But the
>>> frequency of the creak seems too fast for a "one cam" type on the
>>> flywheel, The frequency of creak impulses should be much slower, or
>>> exactly the same speed as the capstan's rotation. But perhaps it wasnt a
>>> single cam but a toothed cog pressed onto the capstan shaft. I had a
>>> Sony TC
>>> The regularly varying whine seems to indicate constant "wow", which
>>> seems to correlate with an unnatural rise and fall of the speaker's
>>> voice. Hard to say if the whine is from the machine or something in the
>>> room. Around 0:40 the operator appears to move the microphone , whereby
>>> the sound of the creak disappears. Around the same time the faint whine
>>> seems also to decrease in level a little. So perhaps an external
>>> microphone was used but (at first) was placed right on the cassette
>>> recorder - a real "no, no". The loud creak sound we hear would have been
>>> much quieter for the operator who would have been much further from the
>>> source of the machine noise, but at least they heard it and appeared to
>>> have the presence of mind to move the mic from the recorder.
>>> At out State Library of Western Australia Oral History digitisation
>>> programme we encountered many cassette recordings made with internal
>>> mics or sometime external mics possibly left sitting on top of the
>>> machine. Many had so much background machine noise the voices were very
>>> hard to listen to or bordered on the unintelligible. What an improvement
>>> these days with motorless flash memory recorders!
>>> Tim Gillett
>>> Perth, Western Australia
>>> ----- Original Message ----- From: "John Chester" <[log in to unmask]>
>>> To: <[log in to unmask]>
>>> Sent: Saturday, July 08, 2017 3:20 AM
>>> Subject: Re: [ARSCLIST] Unexplained sound on oral history cassette
>>>> The distinct midrange tone in this recording varies from about 870 to
>>>> 950 Hz. Spectrogram shows it as a series of scallops. There's a wide
>>>> curve as it drops to 870 Hz, then starts rising again. When it reaches
>>>> 950 Hz, the "creak" happens, and the tone frequency starts dropping.
>>>> I think this was a cheap cassette machine, and the cassette was
>>>> jamming. I assume that playback speed was constant when this transfer
>>>> was done. If the speed was varying during recording, high tape speed
>>>> during recording = lowest tone frequency on playback, and vice-versa.
>>>> When the tone is around 870 Hz, recording speed was normal. As the
>>>> tone rises in frequency, the tape was slowing down during recording. I
>>>> think the "creak" is either mechanical noise from the cassette, picked
>>>> up by a microphone built into the recorder, or electrical noise
>>>> generated by the capstan motor governor when it freaks out because it
>>>> can't rotate the capstan at the correct speed.
>>>> Whatever the cause, it's clearly recorded on the tape. The spectrum of
>>>> the "creak" extends up to about 10 kHz. The voice sounds have a
>>>> similar upper limit. If this noise was generated during playback, it
>>>> would probably extend all the way up to 20 kHz. But I can't imagine
>>>> how it could have been generated during playback.
>>>> -- John Chester
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