AT&T 6300 Programmer's Manual page 460

SOUND
Statement
Syntax
frequency
duration
Example
Remarks
7-304
Produces sound via a speaker.
SOUND frequency, duration
is a numeric expression in the range 37 to 32767. It represents
the Hertz frequency (cycles per second).
is the duration in clock ticks. Clock ticks occur 18.2 times per
second. Duration is an integer expression in the range 0 to 65535.
100 SOUND RND*100+37,2
This statement creates random sounds.
Sound x,D or SOUND 32767,x cause silence.