While I do completely agree that law firm's should optimise their websites for long-tail searches 'e.g how do I start the divorce process', aiming to answer these informal questions, I'm not so sure that Voice Search is such a big deal. Yes - it's influenced how we type, and I too find myself asking Google a full question rather than typing in keywords in recent months. But voice search on a whole? I'm not so sure people really use it other than when they're being lazy. I'm talking from experience here - I have actually used Siri a lot for silly things like "Is [actor_name] dead?" when in mid-debate, or "what's 8 stone in kilograms?" but that's about it. Oh and, obviously, to test it's capabilities: "Siri, do you love me?" and "From now on, call me [offensivewordhere]"
Ask yourself this - when did you last see someone asking Siri a question in public? Even at work, I don't see anyone asking their phones "OK Google. What should I eat for lunch today?" or at the bus stop "What's up Cortana, when's the next bus coming?" More to the point, would someone really use Voice Search to ask questions such as "Siri, which law firm in Bristol can help me divorce my husband?" or "Siri, I just got fired, but it totally wasn't my fault, what do I do?" This is because people are still embarrassed to talk to inanimate objects (understandable) and so if they are on-the-go, they'd rather not look "crazy," (even though mostly everyone has the same tech on their phones) so type a question into Google.
It's easy to see that optimizing your law firm website for keywords doesn't make sense any more. Spoken English is different from written English. Consumers are not inclined to type "personal injury lawyer [city]." Instead, they'll ask Siri or Google, "I was just in a traffic accident. What do I do now?" Here's what smart lawyers will do: Create FAQ pages on your website that sets forth the questions - using the actual words that clients ask - and then answers them in a conversational style. I recommend dictating the answer. Directly answer the question in a straightforward, informal fashion. Write it in a complete sentence, and put the answer in the headline of your copy. Don't begin the answer with a citation, legal reference or introduction. Give the answer as if someone were standing right in front of you.