Normal speaking speed is 150 words per minute, which when recorded equals to a ~1MB M4A file. I typically send 7-minute audio recordings, meaning roughly 1,000 words or about 2 pages of A4 text.

Rather than getting slammed with a wall of text, the recipient of my audio message can listen to it as they're driving, cooking or eating breakfast. Human voice is expressive and the audio message conveys nuance that gets lost texting. Finally, all text messages are being monitored in some fashion but I do believe audio recordings are still relatively safe and private.