The phrase 'speak to whether' is not an idiomatic phrase in English; it does not make sense as written.
In some instances, you could use the phrase 'speak to whether' by substituting it with the phrase 'talk about whether'. For example: I would like to talk about whether this plan is feasible.
Every company is different, so I can't speak to whether or not your application gets read.
"I can't speak to whether I seemed thrilled," he said recently, bristling a little.
"I can't speak to whether or not you are over- or underreporting something," he said.
I can't speak to whether he would be representative of a pundit from South India, a place which has a very different culture from North India.
"We do offer some food at the concession stand, but I can't really speak to whether or not he'll have friends bringing him meals".
Nor does it really speak to whether those potentials for growth can be realized in a sustained way if domestic demand is simultaneously repressed by the stagnation of working class incomes.
Like the memory stick with financial information, the discrepancy spoke to whether Pistorius was a flight risk — this was, after all, a bail hearing.
During this year's local elections, there was one thing I heard time and again from people I spoke to, whether on the doorstep, in their flats or on the street: I don't vote, because it doesn't change anything.
Inclusion speaks to whether individuals have equal access to opportunities and empowerment.
Whoever one spoke to, whether it was Michael Dell, founder of the computer giant carrying his name, Kris Gopalakrishnan of IT services firm Infosys or Wei Jiafu of China Ocean Shipping Group: everybody reported really strong growth and predicted investments and expansion.
As far as the two competitors are concerned, the present-day suffering only speaks to whether or not one of them deserves to be president.
