https://wccftech.com/twitter-is-testing-out-voice-dm-feature-in-a-number-of-countries/

Twitter has apparently started testing a new voice messaging feature for direct messages on the platform. While the feature is not globally available at the time of writing, it is being rolled out in phases, and at the time of writing, users in Japan, Brazil, and India have started receiving this feature.

Voice DMs are going to allow the users to send voice notes or voice messages via direct messages. A similar feature was introduced last year for those who don't remember, which allowed the users to send voice tweets, but the voice DM feature is new. For those wondering, a voice DM can only be 140 seconds long, and the feature will be available for both iOS and Android users.