No response when controlling the Mindstorms EV3 brick over Bluetooth
Using the documentation from here, here, here and here, the command for playing a tone should look something like this:

0x0F, 0x00,            // size of message = 14 bytes
0x00, 0x00,            // message counter = 0 [can by any number]
0x80,                  // command = DIRECT_COMMAND_NO_REPLY
0x00, 0x00,            // 0 bytes for global variables, 0 bytes for local variables
0x94,                  // opSOUND
0x01,                  // CMD = TONE
0x81, 0x32,            // VOLUME = LC1(50) [50%]
0x82, 0x0B, 0x02       // FREQUENCY = LC2(523) [C5]
0x82, 0xF4, 0x01,      // DURATION = LC2(500) [0.5s]