However, we do recommend using an external validation whenever possible, because in-house validations tend to be not very effective. The reason for this is similar to the well-known fact that for instance a programmer that is looking for a bug in his code cannot `see' the error, because he is involved far too deeply in the process. An external observer however often simply points to a quite obvious and simple solution. That's why programmers tend to blab about their programming problems a lot.
The same is true with errors in a speech corpus production process. Therefore it is vital to perform external validations as often as possible.
Very often there is no funding available for external validations or - even worse - there is nobody to be found who might act as an external validation institution. If the speech corpus is produced for a client or a partner institution, the obvious solution is to make that partner or client act as the external validation. However, if you do that, make sure that in your contract there are precise guidelines to be found on what has to be validated when and how (see the following sections). If you have no client or partner in your constellation there remain a few institutions who might be willing to act as a validation institution for your corpus production: SPEX in Nijmegen, Netherlands11.2, BAS in Munich, Germany11.3and University labs that are working on Phonetics and/or Computer Linguistics11.4.