protected function sendRequest(string $hostname, array $params): string
    {
        $url = $hostname . "?" . http_build_query($params);

        $response = $this->getClient()->request("GET", $url);

        if ($response->getStatusCode() != "200") {
            throw new ProviderException("Failed to call the external text-to-speech service");
        }

        return $response->getBody();
    }