WorkerProcessRecycleTime controls the Speech Engine Services worker process - SesWorker.exe. What you're observing is TAH (Telephony Application Host), i.e. w3wp. This is controlled through IIS Manager as a property on the Speech Server application pool.
However, before disabling process recycling, consider increasing the shutdown timeout. When a scheduled (or unscheduled, e.g. due to dropping in new code) recycle occurs, existing calls are allowed to finish, however by default ASP.Net only gives them 30secs. You need to modify your web.config to give them 5 minutes, or whatever value is appropriate for your app. You also need to make sure that the shutdown timeout for your application pool is 1 minute longer. The Speech Application application pool is set to 6 mins by default.
Here's the required contents of your web.config to give calls 5 mins to complete:
<configuration>
<system.web>
<hostingEnvironment shutdownTimeout="300" />
</system.web>
</configuration>