diff --git a/frontend/src/components/FeedbackForm/FeedbackForm.tsx b/frontend/src/components/FeedbackForm/FeedbackForm.tsx
index 869dc92e5..35a8018b4 100644
--- a/frontend/src/components/FeedbackForm/FeedbackForm.tsx
+++ b/frontend/src/components/FeedbackForm/FeedbackForm.tsx
@@ -3,6 +3,7 @@ import { useState, useRef } from "react";
 import Question from "../Question/Question";
 import Button from "../Button/Button";
 import IQuestion from "@/types/Question";
+import { OnResultType } from "@/hooks/useResultHandler";
 
 interface FeedbackFormProps {
     formActive: boolean;
@@ -10,7 +11,7 @@ interface FeedbackFormProps {
     buttonLabel: string;
     skipLabel: string;
     isSkippable: boolean;
-    onResult: (result: any) => void;
+    onResult: OnResultType
     emphasizeTitle?: boolean;
 }
 
diff --git a/frontend/src/components/MatchingPairs/MatchingPairs.tsx b/frontend/src/components/MatchingPairs/MatchingPairs.tsx
index 5b8405196..61f2e62ca 100644
--- a/frontend/src/components/MatchingPairs/MatchingPairs.tsx
+++ b/frontend/src/components/MatchingPairs/MatchingPairs.tsx
@@ -1,4 +1,4 @@
-import React, { useRef, useState } from "react";
+import { useRef, useState } from "react";
 import classNames from "classnames";
 
 import { scoreIntermediateResult } from "../../API";
diff --git a/frontend/src/components/Trial/Trial.tsx b/frontend/src/components/Trial/Trial.tsx
index 853e76d17..9d07551cd 100644
--- a/frontend/src/components/Trial/Trial.tsx
+++ b/frontend/src/components/Trial/Trial.tsx
@@ -1,4 +1,4 @@
-import React, { useState, useRef, useCallback } from "react";
+import { useState, useRef, useCallback } from "react";
 import classNames from "classnames";
 
 import { getCurrentTime, getTimeSince } from "../../util/time";
@@ -6,6 +6,26 @@ import FeedbackForm from "../FeedbackForm/FeedbackForm";
 import HTML from "../HTML/HTML";
 import Playback from "../Playback/Playback";
 import Button from "../Button/Button";
+import Question from "@/types/Question";
+import { OnResultType } from "@/hooks/useResultHandler";
+import { TrialConfig } from "@/types/Trial";
+
+interface IFeedbackForm {
+    form: Question[];
+    submit_label: string;
+    skip_label: string;
+    is_skippable: boolean;
+}
+
+interface TrialProps {
+    playback: any;
+    html: { body: string | TrustedHTML };
+    feedback_form: IFeedbackForm;
+    config: TrialConfig;
+    result_id: string;
+    onNext: (breakRound?: boolean) => void;
+    onResult: OnResultType;
+}
 
 /**
  * Trial is an block view to present information to the user and/or collect user feedback
@@ -13,7 +33,7 @@ import Button from "../Button/Button";
  * If "html" is provided, it will show html content
  * If "feedback_form" is provided, it will present a form of questions to the user
  */
-const Trial = (props) => {
+const Trial = (props: TrialProps) => {
 
     const {
         playback,
@@ -41,13 +61,15 @@ const Trial = (props) => {
 
     // Create result data
     const makeResult = useCallback(
-        async (result) => {
+        async (result: { type: 'time_passed' }) => {
             // Prevent multiple submissions
             if (submitted.current) {
                 return;
             }
             submitted.current = true;
 
+            // TODO: Check if we can find another solution for
+            // the default value of form than [{}]
             const form = feedback_form ? feedback_form.form : [{}];
 
             if (result.type === "time_passed") {
@@ -97,7 +119,8 @@ const Trial = (props) => {
     const checkBreakRound = (values, breakConditions) => {
         switch (Object.keys(breakConditions)[0]) {
             case 'EQUALS':
-                return values.some(val => breakConditions['EQUALS'].includes(val));
+                return values.some(val => breakConditions['EQUALS']
+                    .includes(val));
             case 'NOT':
                 return !values.some(val => breakConditions['NOT'].includes(val));
             default:
diff --git a/frontend/src/hooks/useResultHandler.ts b/frontend/src/hooks/useResultHandler.ts
index 17e0f5dbd..b4c16aff9 100644
--- a/frontend/src/hooks/useResultHandler.ts
+++ b/frontend/src/hooks/useResultHandler.ts
@@ -2,6 +2,8 @@ import { useRef, useCallback } from "react";
 import { scoreResult } from "@/API";
 import Session from "@/types/Session";
 import Participant from "@/types/Participant";
+import Question from "@/types/Question";
+import { TrialConfig } from "@/types/Trial";
 
 interface ResultData {
     session: Session;
@@ -10,18 +12,31 @@ interface ResultData {
     section?: unknown;
 }
 
+interface UseResultHandlerParams {
+    session: Session;
+    participant: Participant;
+    onNext: () => void;
+    state: any;
+}
+
+interface OnResultParams {
+    form: Question[];
+    decision_time?: number;
+    config?: TrialConfig
+}
+
 /**
  * useResult provides a reusable function to handle block view data
  * - collect results in a buffer
  * - handles advancing to next round
  * - finally submits the data to the API and loads the new state
  */
-const useResultHandler = ({ session, participant, onNext, state }) => {
+const useResultHandler = ({ session, participant, onNext, state }: UseResultHandlerParams) => {
     const resultBuffer = useRef([]);
 
     const onResult = useCallback(
         async (
-            result: unknown,
+            result: OnResultParams,
             forceSubmit = false,
             goToNextAction = true
         ) => {
@@ -74,4 +89,6 @@ const useResultHandler = ({ session, participant, onNext, state }) => {
     return onResult;
 };
 
+export type OnResultType = ReturnType<typeof useResultHandler>;
+
 export default useResultHandler;
diff --git a/frontend/src/util/audio.ts b/frontend/src/util/audio.ts
index 3358828ac..a68d7a62d 100644
--- a/frontend/src/util/audio.ts
+++ b/frontend/src/util/audio.ts
@@ -6,7 +6,7 @@ import Timer from "./timer";
 // <audio /> docs: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/audio
 const audio = document.createElement("audio");
 audio.id = "audio-player";
-audio.controls = "controls";
+audio.controls = true;
 audio.src = SILENT_MP3;
 
 // switch to cors anonymous for local development (needed for webaudio)
@@ -27,7 +27,7 @@ document.body.appendChild(audio);
 // expose global
 window.audio = audio;
 
-let _stopFadeTimer = null;
+let _stopFadeTimer: () => void | null = null;
 export let audioInitialized = false;
 
 // Play a silent mp3 to make the audio element play after a user action
@@ -95,7 +95,7 @@ export const fadeOut = (duration = 0.1) => {
 };
 
 // Set audio volume
-export const setVolume = (volume) => {
+export const setVolume = (volume: number) => {
     audio.volume = volume;
 };
 
@@ -114,7 +114,7 @@ export const play = () => {
 };
 
 // Play audio from given time
-export const playFrom = (time) => {
+export const playFrom = (time: number) => {
     setVolume(1);
     play();
     setCurrentTime(time);
@@ -131,7 +131,7 @@ export const stop = () => {
 };
 
 // Load audio from given source
-export const load = (src) => {
+export const load = (src: string) => {
     stop();
     audio.src = src;
 
@@ -140,7 +140,7 @@ export const load = (src) => {
 };
 
 // Set current time t
-export const setCurrentTime = (t) => {
+export const setCurrentTime = (t: number) => {
     audio.currentTime = t;
 };
 
@@ -151,7 +151,7 @@ export const getCurrentTime = () => {
 
 // Add a time update listener that sends current time to the callback
 // Return a function to remove the event listener
-export const onTimeUpdate = (onTimeUpdate) => {
+export const onTimeUpdate = (onTimeUpdate: (time: number) => void) => {
     const callback = () => {
         onTimeUpdate(audio.currentTime);
     };
@@ -164,7 +164,7 @@ export const onTimeUpdate = (onTimeUpdate) => {
 };
 
 // Load audio, and call canPlay when audio is ready
-export const loadUntilAvailable = (src, canPlay) => {
+export const loadUntilAvailable = (src: string, canPlay: () => void) => {
     // The canplaythrough event is fired when the user agent can play the media,
     // and estimates that enough data has been loaded to play the media up to its end
     // without having to stop for further buffering of content.
@@ -178,7 +178,7 @@ export const loadUntilAvailable = (src, canPlay) => {
     if (audio.readyState > 3) {
         removeListener();
         canPlay();
-        return () => {};
+        return () => { };
     }
 
     return removeListener;
@@ -186,7 +186,7 @@ export const loadUntilAvailable = (src, canPlay) => {
 
 // Listen once to the given event
 // After that remove listener
-export const listenOnce = (event, callback) => {
+export const listenOnce = (event: string, callback: () => void) => {
     const remove = () => {
         audio.removeEventListener(event, _callback);
     };