public function validate()
    {
        foreach ($this->inputValidations as $name => $data) {
            $validator = $data['callback'];
            $result = $validator($this);
            if ($result === false) {
                $this->logDebug("Validation FAILED: $name");
                $onError = $data['soundOnError'];
                if (is_array($onError)) {
                    foreach ($onError as $msg) {
                        $this->addPrePromptMessage($msg);
                    }
                } elseif (is_string($onError)) {
                    $this->addPrePromptMessage($onError);
                } else {
                    $this->logDebug("Ignoring validation sound: " . print_r($onError, true));
                }
                return false;
            }
            $this->logDebug("Validation OK: $name");
        }
        return true;
    }