Sound field simulation system and method for calibrating same

• US 4,638,506 A
• Filed: 03/04/1985
• Issued: 01/20/1987
• Est. Priority Date: 03/11/1980
• Status: Expired due to Fees

• Current Assignee: Hok L. Han
• Original Assignee: Hok L. Han
• Inventors: Han, Hok L.
• Primary Examiner(s): Kemeny, E. S. Matt
• Application Number:
  US06/707,527
• Time in Patent Office: 687 Days
• Field of Search: 381/61-63, 364/107
• US Class Current: 704/225
• CPC Class Codes: G10K 15/12 using electronic time-delay networks
• CPC Class Codes: H03G 5/025 Equalizers; Volume or gain control in limited frequency bands
• CPC Class Codes: H04R 29/00 Monitoring arrangements; Testing arrangements for hearing aids H04R25/30; detection of loudspeaker connection H04R5/04; sound-field adaptation dependent on speaker detection H04S7/308
• CPC Class Codes: H04R 29/007 for public address systems public address systems per se H04R27/00
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone

Abstract

The present invention relates to a system for generating within a relatively small enclosed space a sound field corresponding to that in a relatively large enclosed space having specific acoustic characteristics, said system including an input unit adapted to receive at least one primary electric audio signal, the output of which is connected to the input of a signal processing unit having a number (N) of secondary channels, each provided with signal processing means with selectable delay time and selectable gain constant, the N outputs of said channels being intended to produce N secondary electric audio signals, each to be supplied to one of N secondary loudspeaker units placed in said relatively small enclosed space in preselected positions. The invention proposes a system of a kind as mentioned above and comprising a programmable memory for storing parameter groups representative of a number of various relatively large enclosed spaces, i.e. each comprising N delay times and N gain constants, and selecting means for selectively activating just that part of the memory, in which the parameter group representative of a desired enclosed space is stored.

Claims

1. In the method of calibrating a sound field simulation system which comprises the steps of:

(a) switching off secondary loudspeaker units of the simulation system;

(b) generating a first sound source sound at least predominantly corresponding to pink noise;

(c) measuring the sound pressure level of the first sound source sound generated in step (b);

(d) switching on the secondary loudspeaker units;

(e) producing a second sound source sound from said secondary loudspeaker units corresponding to said pink noise of step (b);

(f) measuring the sound pressure level of said second sound source sound; and

(g) adjusting the level of said second sound source sound as measured in step (f) to the level measured in step (c) or differing therefrom by a chosen amount.

2. In the method as defined in claim 1 wherein the level adjusted to in step (g) is the level measured in step (c).

3. In the method as defined in claim 1 wherein the level adjusted to in step (g) is 2 dB lower than the level measured in step (c).

4. In the method as defined in claim 1 wherein the level adjusted to in step (g) is 3 dB higher than the level measured in step (c).