A-Law vs μ-Law: Which Audio Compression Standard Wins in Voice Applications?
A-Law and μ-Law are 8-bit logarithmic codecs that compress 12–14-bit voice samples down to 8 bits, cutting bandwidth in half while keeping speech clear.
People confuse them because both sound “good enough” in casual calls, and most apps quietly pick one based on your region—Europe favors A-Law, North America defaults to μ-Law—so the choice is hidden until a garbled overseas call exposes the mismatch.
Key Differences
A-Law offers slightly wider dynamic range, ideal for softer European landlines; μ-Law gives a 3 dB louder ceiling, suiting the noisier North American PSTN. Bit-for-bit, μ-Law sounds punchier, A-Law gentler.
Which One Should You Choose?
Match the network you serve: deploy A-Law for E1 systems in Europe, μ-Law for T1 in North America. For global apps, detect the user’s locale or store dual encodings to dodge transcoding artifacts.
Can I convert between them on the fly?
Yes, but each 3 dB shift adds quantization noise; keep it under two hops.
Does WhatsApp use either?
WhatsApp sends Opus, then gateways to A-Law or μ-Law only when hitting legacy PSTN legs.