I grew up working in a big chicken house that had to use special bulbs because the vibration from all the fans caused the bulb filaments to vibrate and fatigue. Therefore, when we had a Volvo S70 that went through bulbs like crazy, I assumed it was the vibration from that 5 cyl volvo engine that was harmonic with the elements of all the bulbs we tried. I guess it may have been a voltage issue because the headlights were never particularly bright. We fitted that car with HIDs. The light was better and we never changed a headlight bulb again.