Because Dolby drivers are custom-tuned for specific hardware, you should avoid third-party "driver downloader" sites, which may contain malware or incompatible files.
Where this driver typically appears
: Visit the Acer Support Drivers page. Search for your specific model (e.g., Aspire V3-771) and look for "Audio Driver" under the Windows 7 or 8 section. Dolby Digital Plus Audio Driver 7.3-2.2 Download