This depends on the data type within your "audioBuffer".
32-bit floating point audio samples are usually in the range from -1.0 to 1.0. 16-bit integer audio samples are usually signed in the range -32768 to 32767. 8-bit integer audio samples are very commonly unsigned, with the range being 0 to 255, with 128 being the same as 0.0 in floating point.