Although WhatsApp allows its users to configure the application so that nobody knows that we have read a message. That is, so that a double blue tick does not appear on the text in question when we open the conversation. In the Settings there is no way to configure the "app" to prevent anyone who sends an audio from knowing that we have heard it. However, there is a very easy trick that can be achieved.
To do this, different media can be used, but everyone goes through not hitting the play button and listening to the audio in the conversation we have open with whoever has sent it. On the contrary, we must copy the message and forward it to ourselves. You only need to click on the audio and there will be several options, among which is the "Resend", which is what we must select.
Once this is done, we must send the message to ourselves. We can do it if we keep our own number within the contacts of the "smartphone", something that will allow us to open a conversation with ourselves. It can also be done by creating a group in which we are the only participant.
After forwarding the message to our own chat, we can listen to it there without problem. While we do not play the audio in the conversation that is open with the person who sent it, it will not know if it has been heard or not.
Step by Step
1.- Open the conversation in which we have the audio.
2.- Click on the message and select «Forward».
3.- Forward the audio to a conversation with ourselves or to a group in which we are the only participant.
4.- Listen to the audio within our own conversation. Never do it where we have open with the issuer. .