A sound wallet in cryptocurrency is a novel way of storing private keys using sound or audio. The concept involves encoding a private key as a sound file to provide an additional layer of security, which can then be stored in various formats like a CD, vinyl record, MP3 file, or even an audio file on a digital device.
The private key is converted into a series of audio tones, which is done using specific algorithms that translate the key into sound waves. When access to the private key is needed, the audio file is played back, and software designed to decode the sound can convert it back into the original private key.
Though they may be an unconventional and less obvious method of storage, making it harder for hackers to target, sound wallets require specific tools and knowledge to encode and decode the private key correctly. They are not widely used due to their complexity plus the availability of more straightforward and user-friendly methods like hardware wallets, paper wallets, and software wallets; but sound wallets provide a physical backup that can be stored securely in a safe or other secure location.
However, note that physical media like CDs and vinyl records can degrade over time or be damaged, risking loss of access to funds if the private key is not retrievable.