Browse Prior Art Database

Music Pitch Comparer

IP.com Disclosure Number: IPCOM000093805D
Original Publication Date: 1966-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Ferrier, HA: AUTHOR

Abstract

Drawing A shows a system for comparing sung note 10 with standard frequency 11. The sung audio triggers standard single-shot 12 which produces a standard pulse train at the audio frequency. As the pitch increases, the pulses appear closer together, increasing the pulse area. A similar single- shot 13 converts the reference signal into a similar pulse train. The two outputs are connected in bucking relation to meter 14. The latter averages the net signal and reads up-scale if the singer is sharp and down-scale if flat.

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Music Pitch Comparer

Drawing A shows a system for comparing sung note 10 with standard frequency 11. The sung audio triggers standard single-shot 12 which produces a standard pulse train at the audio frequency. As the pitch increases, the pulses appear closer together, increasing the pulse area. A similar single- shot 13 converts the reference signal into a similar pulse train. The two outputs are connected in bucking relation to meter 14. The latter averages the net signal and reads up-scale if the singer is sharp and down-scale if flat.

It is important to prevent the secondary peaks of the voice signal from falsely triggering voice single-shot 12. Therefore frequency-controlled single-shot 15 is interposed to respond to the voice signal by triggering single-shot 12. The RC timing network of single-shot 15 is controlled by reference frequency 11 to be about 80% of the period of frequency 11.

The circuitry for the frequency-controlled single-shot 15 is shown in drawing
B. The circuit includes tachometer circuit Q6 and Q7 producing a signal proportional to frequency 11 a long-time-constant RC network 20...23 and amplifier Q4 and Q5 for producing a DC current proportional to the filtered signal for charging capacitor 24. The latter is in the timing circuit of single-shots Q1, Q2 and Q3. Capacitor 24 is thus charged to a magnitude proportional to the reference frequency. Capacitor 24 renders the triggering times of the single-shots inversely dependent upon frequency...