As I use the laptop I get a clicking sound coming from the speaker.
It is one short click every 2-3 seconds and just won't go away.

Altering the volume makes no different to the volume of the clicking.
It happens whether I am running applications or with an empty desktop.
Only noticed it happening today and there were a few updates yesterday, amongst them a kernel update.
This only happens when running ubuntu, no clicking in Windows 7 or Chromium OS.

Laptop is an Acer Aspire 5742G
According to lshw:
             description: Audio device
             product: 5 Series/3400 Series Chipset High Definition Audio
             vendor: Intel Corporation
             physical id: 1b
             bus info: pci@0000:00:1b.0
             version: 05
             width: 64 bits
             clock: 33MHz
             capabilities: pm msi pciexpress bus_master cap_list
             configuration: driver=snd_hda_intel latency=0
             resources: irq:43 memory:b4400000-b4403fff
I'm at my wits end with this!