Hall Research AD-340 - Manual (Page 18)

Model AD-340
16
In calculation of delay needed for given distance the unit includes correction
needed for Haas effect. This correction masks localization of delayed audio
source, so the listener still perceives the sound coming from far source.
The maximum number of milliseconds of delay possible is a function of the audio
sampling rate as shown in the table below:
Sampling Rate 32 kHz 44.1 kHz 48 kHz 96 kHz
Max Delay in MSEC 510 ms 370 ms 340 ms 170 ms
The maximum distance also depends on the audio sampling rate and the air
temperature (which affects the speed of sound slightly) as shown below.
Temp 32 kHz 44.1 kHz 48 kHz 96 kHz
Max Delay in
FEET @ 72 °F 550 ft 394 feet 360 ft 169 ft
Max Delay in
METERS @ 23 °C 168 m 120 m 110 m 52 m
The delay values are automatically calculated and synchronized between the
different delay type options by the system, so by changing the values for one
delay type the other values are automatically changed as well. This automatic
calculation also applies to temperature changes. For external delay based on
FEET or METERS the delay in milliseconds is calculated based on the speed of
sound at the given temperature (which can be set by the user), and 20 ms is
added due to the psychoacoustic “HAAS Effect.”
Temperature Compensation: The speed of sound depends on the air
temperature. (Sound slows down with colder temperatures and speeds up with
hotter temperatures.) The table below shows some calculations. The nominal
values for speed of sound are 1130 ft/s at 72°F or 345 m/s at 23° C.
Fahrenheit Speed of Sound ft/ms
32°F 1.08
50°F 1.10
72°F 1.13
90°F 1.14
Celsius Speed of Sound m/ms
10°C 0.337
23°C 0.345
30°C 0.349
45°C 0.357
The more advanced “Temperature Compensation” function on the GUI allows the
user to enter the actual air temperature if desired. The system will automatically
update the max distance allowed in both FEET and METER Delay Types and the
corresponding delay in milliseconds based on either the FEET or METER
settings. (Note: temperature does not affect the video frame delay functions used
for internal delay.) The allowable temperature range is 32-122°F (0-50°C),
although in most cases using the default setting at 72°F (23 °C) will suffice.