Adjust the relative weight between the target and join cost.
festival> (du_voice.set_target_cost_weight currentMultiSynVoice 0.5)
where 0.5 is the weight of the target cost relative to the join cost (default value is 1.0). A target cost weight of zero effectively turns it off altogether and the search will only use the join cost(*). Conversely, a very large target cost weight will mean that the join cost has little effect and candidates will be chosen based on their linguistic features only.
(*) But remember two things:
- candidates are pre-selected on their base diphone type, so that will always match even without any target cost
- candidate lists are pruned based on the target cost, before the search commences, so the target cost will still have an effect – unless you turn off this observation pruning.