Sound: The effect of sample rate, duration and bit depth on: playback quality, size of the sound file

The quality and file size of a sound file are determined by the sample rate, bit depth, and duration. Increasing any of these increases the file size; increasing sample rate or bit depth also improves playback quality.

Key points

• Higher sample rate = more samples per second = better quality AND larger file size.
• Higher bit depth = more bits per sample = more precise amplitude recording = better quality AND larger file size.
• Longer duration = more total samples = larger file size (but does NOT change quality).
• Exam Tip:Duration affects file SIZE but NOT quality. Sample rate and bit depth affect BOTH quality and file size.
• Common Mistake:Saying 'higher duration = higher quality'. Duration has no effect on playback quality — only on file size.
• Common Mistake:Saying 'higher bit depth means more samples per second'. Bit depth is the number of bits per EACH sample (precision). Sample rate is the number of samples per second.
• Exam Example:Table question — sample rate 44kHz→8kHz: file size DECREASES AND accuracy DECREASES. Bit depth 8→16 bits: file size INCREASES AND accuracy INCREASES.