WhatsApp has greatly improved its privacy options, but occasionally there is some trick to avoid the classic check blue, beyond deactivating it. This particular case has to do with one of the most used functions of WhatsApp, and is the one of prevent others from knowing that we have heard the voice notes sent to us, for any reason: either to avoid having to answer at the moment, or because we are not interested in the sender knowing that we have already heard the audio.
And it is that unlike the messages, the voice notes are only marked as heard when we have effectively activated the audio, not simply by entering the message, as it happens with normal chats or with images and videos. To avoid showing the notification of listening, even if we have done it, you just have to forward the voice message without having given the play. How? Very easy.
We have to create a group with us alone, which in addition to this need is also interesting to keep photos, set reminders or save lists or places. If you already have such a group, you just have to forward the voice audio to yourself without listening to it, and play it only from that lonely group.
This will prevent it from being marked as read in the original group and in reality only the user can listen to it, simplest impossible. And at the moment there is no way that WhatsApp can stop this system because of how the system is configured.
However, keep in mind that despite keeping our privacy safe, the truth is that it may be an invasion of the privacy of the sender that originally sends the audio.