Which codec delivers the highest voice quality?

• A. G.729
• B. G.722
• C. G.711
• D. G.726

Answer: (C)

Voice quality is highest when there is no compression and the full audio bandwidth is preserved. G.711 uses uncompressed PCM, transmitting at 64 kbps with 8 kHz sampling. This means the signal is reproduced with no lossy encoding artifacts and with the full speech spectrum available in standard telephony (the 0–4 kHz range). That fidelity gives the most natural, clear sound among the options.

The other codecs trade quality for bandwidth. For example, G.729, G.726, and G.722 all compress audio to save bandwidth, introducing artifacts or limiting frequency content to fit their bitrates. G.722 is wideband and can sound clearer in ideal conditions due to extended high-frequency content, but it is still a compressed format and won’t match the nominal fidelity of uncompressed G.711. Hence, G.711 delivers the highest voice quality.