This can be due to connection variables such as WiFi signal or mobile device connection. Check out your [RSSI in the device health section of the Ring app](https://community.ring.com/t/how-it-works-your-ring-device-rssi-good-vs-poor/229), to ensure for optimal wifi signal. Please also ensure there is not a VPN enabled on your mobile device. If you have a Video Doorbell 3 Plus or a Video Doorbell 4, you might be experiencing the [Pre-Roll feature](https://support.ring.com/hc/en-gb/articles/360038650731-Understanding-the-Pre-Roll-feature) which does not have sound during the Pre-Roll.